Mistake
by Pineslizard
Summary: Dipper sees something he shouldn't have. WARNING: PINECEST


Two minutes.

Three minutes.

Four.

Five.

How long exactly did Mabel like to be alone again? The last time Dipper had seen her this antisocial without mom and dad around was when she was working on the giant social studies project. She hadn't spoken or made contact with anyone for three hours straight, very impressive for a sixteen year old artist who was crazily social.

He eased back into the armchair, trying to focus on what looked like the two hundredth episode of Duck-Tective, but he couldn't get his sister out of his head. It was plaguing him. He wondered what the heck she was doing up there. She had just gotten up and walked away, right in the middle of the episode, mumbling something about the bathroom. Should she be taking this long in the bathroom?

_Why do you even care_? the teen asked himself, closing his eyes before glancing at the stairs for the upteenth time. Why did he want to know where his sister was so badly? He came to the conclusion that it was because Mabel left with little to no explanation, not to mention being rather… quiet, when she did so. Yeah. That must be it.

It took another two minutes before the boy was glancing up the stairwell again while mentally punching himself. _Stop_, he thought angrily. Mabel was probably just distracted by those little sparkly keychains she hung from the lights in the bathroom a few days before. That made sense.

Three more minutes and he had left the chair.

"Why are you doing this," he groaned to himself, very slowly walking up the stairs. Mabel didn't need anyone checking on her. She was an almost hilariously independent person. If she wanted to watch TV, she would come back downstairs and watch TV. If she wanted to stay upstairs, then he wasn't one to stop her. Why did he want to see her so bad? Why did he… miss her?

As he reached the top step, he noticed that the door to the bathroom was wide open. Well, if she had been using it before, she obviously wasn't now. He briefly considered going back downstairs and leaving her to her own devices, before pushing the thought reluctantly from his head. He wanted to know why his sister had left during an episode of her favorite show, and he probably wasn't going to leave until he got an explanation. Probably.

He stopped at her door, which was decorated with an eye-straining amount of glitter and rhinestones. A few posters depicted her current interests, such as the latest popular boyband or cats wearing top hats. He raised his hand to knock, before lowering it, before raising it again. Maybe he could surprise her into a good mood? Was that a good idea? She liked surprises, definitely.

After about thirty seconds of debating whether or not to knock, he finally decided against it. Mabel had been a bit grumpy when she had left, but unlike other people, she never stayed grumpy for long. Jumping through her door and saying a loud hi would perhaps scare her, but would snap her out of whatever funk she was in. At least, he hoped so.

Dipper's hand rested on the doorknob. Why the heck was he still hesitating? He didn't need to. He took a deep breath and thought, _just count down buddy. Three, two, one_…

The door was flung open and Dipper leaped across the threshold, making the craziest face he possibly could (which truthfully was pathetic). From then on in, everything was a blur.

Mabel, noticeably lacking her skirt and even more noticeably lacking underwear, jumped off her bed with a shriek. The young detective who had just stumbled in on her doing… less than appropriate things, covered his eyes and blurted out a series of apologies while stumbling back in the direction he hoped was the door. He inwardly groaned when he felt his back meet the wall. Oh boy.

"Dip!" his sister shouted. "What are… I… Why didn't you knock?"

"I wanted to surprise you," Dipper moaned, covering his face completely in a failed attempt to hide the enormous blush creeping over him. The boy was about three seconds from just flopping to the floor and feigning death. He hadn't been this embarrassed since that weird kid from down the street pantsed him during a school speech.

"Well… I… um…" Mabel trailed off. He didn't dare peek, but he could hear her pulling her underwear hastily back on. "Wow. Awkward."

He didn't speak. He waited for what his sister was going to say next, trying to make as little noise as he possibly could. A loud exhale escaped him and he mentally beat himself to a pulp.

"Uh… so… yeah," his sister continued in a rather high pitched voice. "Um… Don't really know what to say here… Maybe, uh, can you get out of my room for a sec?"

Dipper scrambled out the entrance as fast as he could without looking. If he had been in a different position, he probably would have found humor in the way he continuously smacked into the wall, looking for the doorway.

Once in the hall, he let himself collapse against the wall. It felt as though everything had been drained from him. His face was still a brilliant shade of red, and he could feel his heart pounding. Well. That had just happened. He had just walked in on Mabel.

He felt the beats suddenly increase as the door creaked slightly. His sister peered from the doorway, wincing slightly at the sight of him curled up on the floor. She slowly approached him, apparently waiting for him to run the other direction or yell at her. He did neither, instead looking up and revealing the tremendous blush that spread to his ears.

"Sorry about that," she whispered in an almost painfully squeaky voice. She immediately flinched at her own tone.

"Uh, it's ok," Dipper replied, a bit too fast to be considered normal. "I mean, it's fine! Uh, lots of people," he hid his face in his vest, "uh… yeah. It's… it's fine."

Mabel looked down at her tentative brother and covered her face. "I'm serious, bro," she mumbled. "I'm gross. I'm super sorry."

Dipper nodded a tiny bit, staring into her half-worried and half-humiliated eyes. He felt waves of shame cascading over him. His poor sister. Had the roles been reversed, he would probably be drowning in embarrassment right now. "It's fine," he insisted again in a very small voice. He jolted a bit in shock when one of her hands subconsciously rested on his shoulder.

Realizing what she had done, Mabel immediately withdrew her appendage and used it to cradle her face. She muttered a mixture of apologies and curses under her breath, visibly smacking her head against her palm several times. Dipper couldn't describe the feeling that burned through him in that moment. Sure, some of it was definitely feeling sorry for her, but the rest felt very different. This was a feeling he couldn't remember ever experiencing before, and he honestly didn't like it much.

The young detective reached out and held her hand, causing her eyes to snap up and meet his. He blushed a bit more, if that was possible, and offered a miniscule wave. Her tiny giggle, as small as it was, made butterflies struggle to escape his stomach. However, she quickly squished it down.

"I guess you kinda want to go away now," she murmured quietly, breaking the eye contact to stare blankly at the floor.

Dipper didn't reply, though every cell in his brain was screaming at him to disagree. Mabel looked terrible. All he wanted to do was hug her and gently hold her hand until she felt better, but he knew that was definitely not the way to solve something like this.

"Do you want to… Er, be left alone?" he asked in reply. Though he definitely felt something plummeting as she nodded, he couldn't deny that would probably be the best choice for him, too. He slowly rose to his feet before climbing down the stairs, leaving his sister back in the hall.

As he settled on the couch, he mentally vowed to do something for her later, just to show her that nothing had changed between them. Something small, like inviting her to an 80's movie marathon or something. She would like that. Yeah.

He settled back into the cosy yellow armchair and reached for the remote. Switching the TV off, he mentally kicked himself for walking in on her while she tried to relieve herself, and even more for not denying it when she beat herself up for being gross. It wasn't like he didn't do the same thing. Not that she would know that.

He sighed and held his face in his hands. Later. Later, he would make up for this.

* * *

><p><strong>AN: OH GOD I WROTE PINECEST. THIS IS BAD. FORGIVE ME.**

**First fanfiction on this account, too. Why do I have to like this? This is weird! Why did I just write a oneshot? Why? Why? WHY?**

****UGH PINECEST. Doublepines, if you weren't so awesome, I would kill you.****


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